How and why plant ionomes vary across North American grasslands and its implications for herbivore abundance.

Autor: Kaspari M; Geographical Ecology Group, Department of Biology, University of Oklahoma, Norman, Oklahoma, 73019, USA., de Beurs KM; Department of Geography and Environmental Sustainability, University of Oklahoma, Norman, Oklahoma, 73019, USA., Welti EAR; Geographical Ecology Group, Department of Biology, University of Oklahoma, Norman, Oklahoma, 73019, USA.; Senckenberg Research Institute and Natural History Museum Frankfurt, Gelnhausen, 63571, Germany.
Jazyk: angličtina
Zdroj: Ecology [Ecology] 2021 Oct; Vol. 102 (10), pp. e03459. Date of Electronic Publication: 2021 Aug 05.
DOI: 10.1002/ecy.3459
Abstrakt: Plant elemental content can vary up to 1,000-fold across grasslands, with implications for the herbivores the plants feed. We contrast the regulation, in grasses and forbs, of 12 elements essential to plants and animals (henceforth plant-essential), 7 essential to animals but not plants (animal-essential) and 6 with no known metabolic function (nonessential). Four hypotheses accounted for up to two thirds of the variation in grass and forb ionomes across 54 North American grasslands. Consistent with the supply-side hypothesis, the plant-essential ionome of both forbs and grasses tracked soil availability. Grass ionomes were more likely to harvest even nonessential elements like Cd and Sr. Consistent with the grazing hypothesis, cattle-grazed grasslands also accumulated a handful of metals like Cu and Cr. Consistent with the NP-catalysis hypothesis, increases in the macronutrients N and P in grasses were associated with higher densities of cofactors like Zn and Cu. The plant-essential elements of forbs, in contrast, consistently varied as per the nutrient-dilution hypothesis-there was a decrease in elemental parts per million with increasing local carbohydrate production. Combined, these data fit a working hypothesis that grasses maintain lower elemental densities and survive on nutrient-poor patches by opportunistically harvesting soil nutrients. In contrast, nutrient-rich forbs use episodes of high precipitation and temperature to build new carbohydrate biomass, raising leaves higher to compete for light, but diluting the nutrient content in every bite of tissue. Herbivores of forbs may thus be particularly prone to increases in pCO 2 via nutrient dilution.
(© 2021 by the Ecological Society of America.)
Databáze: MEDLINE
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